One of the really "Big Ones" to shake the United States was a magnitude-9.0 earthquake along the Pacific Northwest coast more than 300 years ago, before the arrival of huge numbers of people and development, that sent a catastrophic tsunami to Japan.
Were something like that 1700 quake to occur today — and it certainly could, seismologists say — enormous destruction and loss of life would result in a region that is home now to big cities and millions of people.
The magnitude-8.8 earthquake that rocked Chile and sent tsunami fears across the Pacific on Saturday — nearly seven weeks after the enormously deadly quake that destroyed parts of Haiti— serves as a vivid reminder of the perils posed to the United States by countless fault lines and shifting plates.
"It's not a matter of if, only of when an event like this strikes the people of the United States," says Marcia McNutt, director of the U.S. Geological Survey. "Shame on us if we don't prepare